Response Validation in Google Forms: Numbers, Text, Email, Length
Quick answer: Click a Short answer or Paragraph question, open the ⋮ menu, and choose Response validation. Pick a type — Number, Text, Length, or Regular expression — set the condition, and write a custom error message. Google Forms then blocks submission until the answer matches your rule.
Free-text questions are the easiest place for messy data to sneak into a form — a phone number typed with letters in it, an email missing the "@," or a comment field that runs on for a thousand words. Google Forms' built-in response validation catches these before submission, rejecting an answer and showing an error message until it fits the rule you set. This guide walks through every validation type, how to write error messages people actually understand, and where validation's limits are.
How to turn on response validation
- Click a Short answer or Paragraph question — validation is only available on these two text-based question types.
- Click the three-dot menu (⋮) at the bottom of the question box.
- Select "Response validation." A new row appears under the question with a dropdown for the validation category.
- Choose a validation type (Number, Text, Length, or Regular expression) and set the specific condition and value.
- Add a custom error message in the "Custom error text" field so respondents understand exactly what went wrong and how to fix it.
The validation types, explained
- Number. Restricts the answer to a numeric value, with sub-conditions like "greater than," "less than," "between," "equal to," "not equal to," "is a whole number," or "is a number" generally. Useful for ages, quantities, or ratings entered as free text.
- Text. Checks the text itself against a condition: "contains," "doesn't contain," "is email address," or "is URL." The "is email address" option is a fast way to guarantee a properly formatted email without writing your own pattern.
- Length. Caps or floors the character count with "maximum character count" or "minimum character count." This is the go-to option for keeping comment fields from running too long, or making sure a short-answer field isn't left with just one or two throwaway characters.
- Regular expression. The most flexible option, with three modes: "matches," "doesn't match," and "contains." This lets you write a custom pattern for anything the built-in options don't cover — a loosely formatted phone number, a specific ID format, or a domain restriction.
Writing a helpful custom error message
The default error text Google Forms shows is generic ("Response must be a number," for example), which doesn't always tell a respondent what actually went wrong on their end. Always fill in the Custom error text field with something specific and actionable — for instance, instead of leaving the default in place, write "Please enter a number between 1 and 10" or "Please use your company email ending in @yourcompany.com." A clear, specific message saves respondents a guessing game and reduces abandoned forms.
Real examples
- A loosely formatted phone number. Use Regular expression, "matches," with a pattern like
^[0-9\s\-\+\(\)]{7,15}$, which accepts digits, spaces, dashes, parentheses, and a leading plus sign within a reasonable length range — loose enough to accept different regional formats without being overly strict. Pair it with an error message like "Please enter a valid phone number (digits, spaces, and dashes only)." - Capping a comment field. On a Paragraph "Additional comments" question, use Length, "maximum character count," and set it to something like 500. Set the error text to "Please keep comments under 500 characters" so people know the limit before they hit it, not just after.
- Requiring a company email domain. Use Regular expression, "matches," with a pattern like
^[A-Za-z0-9._%+-]+@yourcompany\.com$to only accept addresses ending in your organization's domain. This is useful for internal forms that should only be filled out by employees, layered on top of (not instead of) proper access restrictions if the form contains sensitive data.
Validation limitations
Response validation only evaluates a single question against its own rule — it has no awareness of any other question on the form. That means you can't set up a rule that checks whether two fields match each other, such as confirming a "Confirm email" field is identical to the "Email" field above it, or that an "End date" comes after a "Start date." If you need cross-question logic like that, you'll either need to accept the limitation, use a workaround like combining both pieces of information into one instruction-heavy question, or handle that kind of validation downstream once responses land in a connected Google Sheet.
Validation also only applies to Short answer and Paragraph questions. Other question types — multiple choice, checkboxes, dropdown, linear scale — don't have a validation option because respondents are already restricted to a fixed set of choices you've defined, so there's nothing free-form to validate.
FAQ
Which question types support response validation?
Response validation is available on Short answer and Paragraph text questions. Other question types like multiple choice or checkboxes don't need validation since respondents pick from fixed options.
Can I validate that an answer matches a specific format like a phone number?
Yes, using the Regular expression validation option. You can write a pattern that matches a loose phone number format and pair it with a custom error message explaining the expected format.
Can Google Forms validate one answer against another question?
No. Response validation only checks a single question's own answer against its own rule. It cannot compare two different questions to each other, such as confirming two email fields match.
What happens if a respondent enters an invalid answer?
Google Forms shows your custom error message (or a default one) directly under the question and blocks submission until the respondent corrects the answer to match the validation rule.